Electric valve converting system and excitation apparatus therefor



Dec. 12; #1 933. MQRACK 1,939,458 ELECTRIC vALvz convzn nue SYSTEM ANDEXGITATION APPARATUS rasasron Filed'June 22, 1933 Inventor:

Marvin M. Mof'ack.

Patented Dec. 12, 1933 PATENT OFFICE ELECTRIC VALVE CONVERTING SYSTEMAND EXCITATION APPARATUS THERE- FOR Marvin M. Morack, Schenectady. N.Y.,' assignor to General Electric Company, a corporation of New YorkApplication June 22, 1933. Serial No. (av-L052 9 Claims.

My invention relates to electric valve converting systems and moreparticularly to new and improved apparatus for exciting the controlelements of the electric valves of such converting systems.

Heretofore, there have been devised numerous electric valve convertingsystems for transmitting energy between direct and alternating currentcircuits, direct current circuits of different voltm ages, orindependent alternating current circuits of the same or differentfrequencies. Many of these systems have included a distributor apparatuseffective to render conductive the several electric valves in apredetermined sequence to transfer the current between the severalterminals of the load circuit of the system. In many cases, however, itis desirable to eliminate the moving contacts and other disadvantagesinherent in a mechanical distributing apparatus. My

invention relates more particularly to an excitation apparatus which mayreplace the conventional mechanical distributor in the arrangements ofthe prior art.

It is an object of my invention, therefore, to

5 provide an improved electric valve converting system and an excitationapparatus therefor which will overcome the disadvantages inherent in themechanical distributor apparatus of the prior art and which will besimple and reliable in operation.

It is another object of my invention to provide an improved electricvalve converting system and an excitation apparatus therefor which willrender conductive the several electric valves in a predeterminedsequence and which will elimicircuits and a device for successivelyproducing variations in the impedances of the devices which,

when the value of their impedance is a minimum.

substantially bypass the sources of control potential from the controlelements of the electric valves. For example, the impedance devices mayconstitute reactance devices having open circuit magnetic paths orcores, in which case there is also provided an inductive member, such asa magnetic vane, in asymmetric inductive relation to the magnetic pathsof the several reactance devices. The. inductive member and thereactanoe devices are relatively rotatable and there is provided meansfor producing relative rotation to successively vary the impedance ofthe reactance devices and successively energize the control elements ofthe electric valves to render them conductive. 'It may also be desirableto provide an additional impedance device or reactance device in serieswith the control circuit of each of the electric valves and to varysuccessively the impedance of this series reactance alternately withrespect to the shunt reactance of each of the control circuits.

For a better understanding of my invention, together with other andfurther objects thereof, reference is had to the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims. The single figure of the drawingillustrates diagrammatically an electric valve converting system fortransmitting energy from a single phase alternating current supplycircuit to a quarter phase alternating current motor to which is appliedmy improved valve excitation apparatus.

Referring now more particularly to the drawing, there is illustrated anarrangement for transmitting energy from a single phase alternatingcurrent supply circuit 10 to.a quarter phase alternating current motor11 of the synchronous type comprising armature phase windings 12 and 13and a rotatable field winding 14. The field winding 14 may be connectedin series with the armature winding, as illustrated, in case it isdesired to give the motor series characteristics, or in case shuntcharacteristics are desired the field winding 14 may be separatelyexcited in any well known manner. As illustrated, the field winding 14is connected between the electrical neutrals of the phase windings l2and 13, a circuit which 95 carries unidirectional current, as will beexplained more fully hereinafter. A variable resistor 15 may beconnected across the field Winding 14 to regulate the speed-torquecharacteristics of the motor, in which case it is preferable also to in-100 clude a reactor. 16in series with the-parallel connected winding 14and resistor 15.

The terminals of the armature phase winding 12 are connected to thesupply circuit 10 through two groups of similarly connected electricvalves 105 17 and 18, and 19 and 20, respectively. Similarly thearmature phase winding 13 is connected. to the supply circuit 10 throughtwo groups of electric valves 21 and 22, and 23 and 24, connected to thecircuit 10 with a polarity opposite to that 0 of the electric valves17-20, inc. Each of the electric valves 17-24, inc., is provided with ananode, a cathode and a control electrode and may be of any of theseveral types well known in the art, although I prefer to use valves ofthe vapor or gaseous electric discharge type.

In order to render the valves conductive in a predetermined sequence,the control electrodes, or grids, of the pairs of valves 17-18, 1929,etc, are connected to their respective cathodes through current limitingresistors '25, negative bias batteries 26 and secondary windings of gridtransformers 27, 28, 29 and 30, respectively, although in someinstances, the negative bias batteries 26 may be satisfactorily omitted.The

' primary windings of the grid transformers 27-30, inc., are excitedfrom the alternating current supply circuit 10 through any suitablephase adjusting means such as an impedance phase'shifting circuit 31 ofa typewell known in the art. In order to control the energization of theseveral gridtransformers 27-30, inc., to render conductive the electricvalves in a predetermined sequence, there are connected in parallel. tothe primary windings of the transformers 27-30, inc.,

impedance devices illustrated as reactance devices 32-35, inc.,respectively, each provided with an an open circuit magnetic'core,although under open magnetic core member. There. are also connected inseries with the primary windings of the several transformers 27-30,inc., the several impedance devices illustrated'as reactance devices36-39, inc., respectively, also each provided with certain operatingconditions these last impedance devices may be omitted. An inductivemember 40 connected to be rotated by the motomll is mounted inasymmetric inductive relation to the magnetic circuits of the severalreactance devices 32-39, inc. The member 40 may be composed of magneticmaterial and may take the form of a segment of a disk as illustrated, ora segment of a cylinder, or some other mutilated symmetrical form. Asindicated in the drawing; the magnetic circuits of the reactance devices32-39, inc., are symmetrically mounted adjacent the path of rotation ofthe inductive member 49, the series connected reactance device and theshunt. connected reactance device associated with each grid Itransformer being displaced in phase 180 elec- 'trieal degrees referredto the motor, which in the case of the two-pole motor illustrated, isalso 180 mechanical degrees. However, this-featuregpf controllingtheconductivity of a group ofelectric valves by a distributor mechanismdriven by 'a' motor energized through the valves forms no part of mypresent invention, but is disclosed and broadly claimed in a *copendingapplication of E. F. W. Alexanderson, Serial No. 638,361, filed May 11,1923, and assigned to the same assignee as-the present application.

The general principles of operation of the above described apparatus fortransmitting energy from the alternating current circuit 10 to the motor11 will be well understood by those skilled in the art, or may be foundexplained in detail in a copending application of E. F. W. Alexanderson,Serial No. 598,380, filed March 12, 1932, and assigned to thesame-assignee as the present application. That application discloses andbroadly claims the above-described power circuit, which forms no part ofthe present invention. Assuming that the motor field winding 14 and theinductive member 40are substantially in the positions illustrated, andthat the "phase shifting circuit .31 is so adjusted that the potenthesame time, the magnetic circuits of the reactance devices 32 and 37, 35and 38 are opened and their impedances are a minimum.. That is, theimpedances of the devices .36 and 39 in series with the primary windingsof the transformers 27 and 30 are a maximum, while the impedances of thedevices 32 and 35 in parallel with the primary windings of thesetransformers are a minimum so that these transformers are substantiallydeenergized and the associated valves 17 and 18 and 23 and 24 aremaintained non-conductive by their respective negative bias batteries26. At the same time, the impedances of the devices 37 and 38 in serieswith the primary windings of-the transformers 28 and 29, respectively,are a minimum while the impedances of the devices 33 and 34 in parallelwith the primary windings of the transformers 28 and 29 are a maximum sothat these transformers are fully energized from the circuit 10 throughthe impedance phase shifting circuit 31 to render conductive the groupsof valves 19 and 20, and 21' and 22. s

The two pairs of valves 19 and 20, and 21 and 22 comprise a full waverectifying circuit 'motive force created by the current flowing in thearmature windings 12 and 13 will be in such a direction as to cause atorque upon the motor field 14 and initiate a rotation of the motorwhich,

it will be assumed, is in a counter-clockwise direction.

When the motor 11 has rotated through approximately 90 electrica'ldegrees the magnetic vane 40 will have moved to open the magneticcircuits of the reactance devices 33 and 36 and to close the magneticcircuits of the reactance devices 32 and 37, thus energizing the primarywinding of the grid'transformer 27 and deenergizing the primary windingof the grid transformer 28. The electric valves 17 and 18 now becomeconductive while valves 19 and 20 are rendered nonconductive and currentis transferred from the upper to the lower terminal of the armaturephase winding 12. The magnetometive force of the motor 11 is therebyadvanced through substantially 90 electrical degrees and produces atorque on the motor field 14 to rotate it through an additional 90degrees. In this manner current is successively commutated between theseveral terminals of the armature windings 12 and 13 to produce arotating magnetomotive force and a rotation of the motor 11. Themagnetic member 40 is effective to close the magnetic circuit of onlythose -reaciuamce demagnetic circuits are open to substantiallydeenergize their associated grid transformers, the series connecteddevices36-39 inc., may be omitted While I have described what I atpresent consider the preferred embodiment of my invention, it will beobvious to those skilled in the art that various changes andmodifications may be made without departing from my invention, and I,therefore, aim in the appended claims to cover all suchchanges andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. In acontrolled electric valve converting system, apparatus forexciting the control elements of the valves of the system in apredetermined sequence comprising a control circuit for each of saidvalves including a source of control potential, an impedance deviceconnected in shunt to each of said control circuits, and means forproducing successive variations in the impedances of said devices.

2. In a controlled electric valve converting system, apparatus forexciting the control elements of the valves of the system in apredetermined sequence comprising a control circuit for each of saidvalves including a source of control potential, a reactance deviceconnected in shunt to each of said control circuits and provided with anopen magnetic circuit, an inductive member in asymmetric inductiverelation to said magnetic circuits, and means for producing relativerotation between said member and said magnetic circuits.

3. In a controlled electric valve converting system, apparatus forexciting the control elements of the valves of the system in apredetermined sequence comprising a control circuit for each of saidvalves including a source of control potential, a reactance deviceconnected in shunt to each of said control circuits and provided with anopen magnetic circuit, a magnetic vane rotatably mounted adjacent themagnetic circuits of said reactance devices, and means for rotating saidvane to successively close the magnetic circuits of said reactancedevices.

4. In a controlled electric valve converting system, apparatus forexciting the control elements of the-valves or the system in apredetermined sequence comprising a control circuit for each of saidvalves including a source of control potential, an impedance deviceconnected in shunt toeach of said control circuits, an impedance deviceconnected in series with each of said control circuits, and means forproducing successive variations in the impedances of said devices, thevariation in the impedances of the series and shunt devices of eachcontrol circuit being effected alternately.

5. In a controlled electric valve converting system, apparatus forexciting the control elements of the valves of the system in apredetermined sequence comprising a control circuit for each of saidvalves including a source of control potential, a reactance deviceconnected in shunt to each of said control circuits, a reactance deviceconnected in series with each of said control circuits, said reactancedevices having open magnetic cores, a member in asymmetric inductiverelation to said 7 tion of said member.

magnetic cores, and means for producing relative rotation between saidmember and said cores, the series and shunt connected devices beingdisplaced in phase with respect to the relative rotations, the seriesand shunt devices of each control circuit being displaced in phase withrespect to the rotation ofsaid magnetic member, and means for rotatingsaid magnetic member.

7. In a controlled electric valve converting system for transmittingenergy from a supply circuit to a load circuit including an alternatingcurrent motor, said system including a plurality of valvesinterconnecting said supply circuit with the several terminals of saidload circuit, apparatus for exciting the control elements of the valvesto render said valves conductive in a predetermined sequence comprisinga control circuit for each of said valves including a source of controlpotential, an inductance device connected in shunt to eachv of saidcontrol circuits, a rotatable member in asymmetric inductive relation tosaid inductance devices and connected to be driven by said motor.

8. In a controlled electric valve converting system for transmittingenergy from a supply circuit to a load circuit including an alternatingcurrent motor, said system including a plurality of valvesinterconnecting said supply circuit with the several terminals of saidload circuit, apparatus for exciting the control elements of the valvesto render said valves conductive. in a predetermined sequence comprisinga control circuit for each of said valves including a source of controlpotential, a reactance device connected in shunt to each oi! saidcontrol circuits, a reactance device connected in series with each ofsaid control circuits, said reactance devices having open magneticcores, a magnetic member in asymmetric inductive relation to saidmagnetic cores and connected to be driven by said motor, the series andshunt connected devices being displaced in phase with respect to therotation of said magnetic member.

9. In combination, a supply circuit, a load circuit provided with aplurality of terminals, a plurality of electric valves interconnectingsaid supply circuit and the several terminals of said load circuit, eachof said valves being provided with a control element, a control circuitfor each oisaid 135 control elements, an impedance device connected inshunt to each of said control circuits, an impedance device connected inseries with each of MARVIN M. Monacx.

